In the medical field, it is a very common procedure, and often very necessary, to conduct a bleeding time test which measures the time required for the cessation of bleeding following a skin incision. This test is medically important because extended or prolonged bleeding time can be associated with, for example, a lack of or a great excess of platelets, abnormality of platelet function, coating of platelets by specific proteins or foreign materials or the action of certain drugs; e.g., aspirin.
Although the bleeding time test procedure was first described approximately ninety years ago, it did not receive general acceptance until the 1940's at which time the test's sensitivity was increased by making a skin incision on the forearm of the patient while maintaining a blood pressure cuff inflation to maintain venostasis at a standardized level. Using this procedure, a technologist simultaneously starts a stopwatch while making the incision. The emerging blood is then gently blotted every thirty seconds. The cessation of bleeding is defined as the time at which the blotting paper is no longer stained by the emerging blood. This amount of time is generally recorded to the nearest half minute.
Disposable bleeding time devices were first introduced in 1978 to facilitate automation and convenience. These devices improved the acceptance of the test by both the patient and the operator. However, the results were still subject to a variety of technical variables. Additionally, these devices were significantly more expensive than previous methods. This hindered the acceptance of such devices in many countries around the world. Importantly, different disposable devices evolved over time which were functionally quite dissimilar so that the results were not comparable. Thus, standardization remained an elusive goal in bleeding time testing.
An important bleeding time testing device is known as the TRIPLETT™ bleeding time testing device. This was named after the noted physician in blood coagulation and hematopathology, Dr. Douglas Triplett. This device is presently manufactured and sold by Helena Laboratories of Beaumont, Tex. This device met the goal of global standardization in bleeding time testing and utilizes advanced technology at a universally affordable price. This was a product that provided a new level of value to automated, disposable bleeding time devices. This TRIPLETT™ bleeding time testing device was designed to be user and patient friendly, virtually painless, and to mimic the incision motion of the original bleeding time method. The device makes a standardized surgical incision one millimeter deep by five millimeters long for accurate sensitive bleeding time testing. The blade automatically retracts after incisions so as to ensure safety. The device includes a large contact surface that distributes the downward force over a wider area of skin so as to reduce the potential for deep non-standardized cuts. This device is presently subject to patent protection under U.S. Pat. Nos. 5,662,672 and 5,733,300.
In the past, various U.S. patents have issued in association with devices for creating incisions in skin. There is a wide variety of inventions specifically geared toward creation of skin incisions for use in the medical field for blood sampling and bleeding time testing. U.S. Pat. No. 4,535,769, issued on Aug. 20, 1985 to Burns, discloses an automatic retractable lancet assembly that includes a housing with a sharp-pointed lancet movably mounted therein. A depressible plunger and slide mechanism actuates the movement of the lancet outwardly from the housing, which is an elongate cylinder.
U.S. Pat. No. 5,527,333, issued on Jun. 18, 1996 to Nikkels et al., presents a disposable blood sampling device for a precise incision of predetermined length and depth in the skin of a patient. A trigger is slidably disposed in the opening in the top surface of the device, which is generally cylindrical in shape. A single spring, only, is extended by the trigger when the device is actuated.
U.S. Pat. No. 5,529,581, issued on Jun. 25, 1996 to Cusack, also teaches a lancet device and associated method used for obtaining a blood sample from a patient. A slotted aperture is formed through a safety housing in the region of the housing placed against the skin. An invertible spring member is a curved structure that automatically inverts into a generally oppositely curved orientation when the invertible spring member is flattened by a predetermined degree. U.S. Pat. No. 5,797,940, issued on Aug. 25, 1998 to Mawhirt et al., describes a device for making an adjustably sized incision in skin. The device comprises a housing having a slotted opening; a blade; a triggering mechanism and an incision size adjusting mechanism associated with the housing for selectively adjusting the size of the incision.
U.S. Pat. No. 5,395,388, issued on Mar. 7, 1995 to Schraga, describes a single use disposable lancet device including a generally cylindrical housing wherein a spring is contained, the spring including a first end fixed within the housing and having a movable second end zone with a pointed blade or terminal end, the second end zone being movable relative to a normal position with the pointed terminal end contained within the housing and adjacent a first opening in the housing.
A study of the prior art also reveals a number of low-cost devices for creating incisions in skin. For example, U.S. Pat. No. 5,851,215, issued on Dec. 22, 1998 to Mawhirt et al., teaches a low-cost safety lancet for creating a skin incision. The lancet contains a unitarily formed plastic body, thereby making the lancet device easy to manufacture at a low cost. The lancet device includes a blade beam having a cutting blade disposed at one end for generating an incision in a patient's skin. U.S. Pat. No. 5,584,846, issued on Dec. 17, 1996 to Mawhirt et al., presents another low-cost safety lancet for creating a skin incision. The lancet contains a unitarily formed plastic body, containing a resilient spring loop that attaches an arm element to an opposing base element. A blade is disposed on the arm element.
Finally, a number of U.S. patents have issued in this field of art using an enclosed spring structure. For example, U.S. Pat. No. 4,064,871, issued on Dec. 27, 1977 to W. J. Reno, teaches a bleeding time testing device that includes a housing having a surface with a slot defining a longitudinal opening into the housing. A blade is mounted within the housing for movement of the blade tip through and along the slot. Biasing springs are provided within the housing to urge the blade through the slot a predetermined distance and along the slot for a predetermined length to control the depth and length of an incision produced with the device. A trigger is provided to initiate movement of the blade along with a safety pin to prevent the inadvertent activation of the device.
U.S. Pat. No. 5,314,441, issued on May 24, 1994 to Cusack et al., presents a lancet device with a blade support arm pivotably secured within a hollow housing. The pivot connection between the blade support arm and the housing is formed by a pivot pin, which is free to reciprocally move within the slot receptacle. The rotation of the blade support arm about the pivot pin is implemented by a bias spring. The blade of the device implements an incision and is again retracted into the housing traversing a “tear drop” shaped path.
U.S. Pat. No. 6,221,089, issued on Apr. 24, 2001 to Mawhirt et al., teaches a device for making an incision in skin, having a housing with a slotted opening, and a triggering mechanism disposed within the housing for propelling a blade coupled thereto, through the slotted opening of the housing to make an incision in the skin. The triggering mechanism includes a finger engageable trigger located external to the housing for actuating the triggering mechanism and a spring anchoring assembly for automated machine arming the device after the triggering mechanism has been assembled into the housing.
One of the problems associated with the use of the TRIPLETT™ device is that the force applied to actuate the device is off-center from the location at which the blade emerges from the cutting surface. As such, variations of pressures applied to the device can occur. As a result, the bleeding time testing can have a lack of consistent testing. Angular deflections of the cutting surface can also occur by the off-center application of pressure to the actuator of such cutting device. As such, a need has developed for a device for actuating such blood acquisition devices such that the pressure of actuation will be directly above the location of the incision.
U.S. Provisional Application Ser. No. 60/393,971, filed on Jul. 25, 2002, by the present applicant, describes a constant force actuator for a blood acquisition device. This constant force actuator is externally applied to an existing blood acquisition device. The blood acquisition device includes a body having a bottom surface from which a cutting blade can emerge so as to carry out an incision. The body includes a switch pin actuator that extends outwardly of the top surface in the acquisition device body. The switch pin is movable between a pre-actuating position and an actuating position. A safety tab is removably positioned between the switch pin actuator so as to retain the switch pin actuator in its pre-actuating position. The safety tab is to be removable so as to enable the testing device to be actuated by moving the switch pin from the pre-actuating position to the actuating position. The cutting blade is cooperative with the switch pin actuator to move outwardly of the bottom surface of the body of the testing device when the switch pin is moved to the actuating position.
In this provisional patent application, a constant force device is mechanically attached to the surface of the body of the blood acquisition device. The constant force device has a housing that is mounted onto the top surface of the blood acquisition device so as to extend parallel to the bottom surface of the device. A suitable spring clip is provided on the housing so as to allow the actuator housing to be affixed to the body of the blood acquisition device. A slide frame is mounted on the housing so as to be in slidable relationship to the housing. The slide frame is movable between a pre-activated position to an activated position. In the pre-activated position, the slide frame has a surface which resides against the switch pin actuator in the pre-activated position. A spring is mounted so as to be cooperative with the slide frame so as to urge the slide frame to the actuated position. An actuator button is slidably mounted on the housing so as to be slidable in a direction transverse to the plane of the bottom surface of the blood acquisition device. When the actuator button is depressed, the spring associated with the slide frame urges the slide frame in a horizontal direction parallel to the bottom surface of the blood acquisition device and thereby moves the switch pin actuator from the pre-actuating position to the actuating position. The actuator button is positioned directly above the center line of the cutting blade during the incision procedure.
It is an object of the present invention to provide a skin incision device that will not make the incision until a controlled vertical force is applied against the subject tissue.
It is another object of the present invention to provide a skin incision device that removes the variations of force that are applied by different operators at the time the incision is performed.
It is another object of the present invention to provide a skin incision device which allows the actuation force to be easily altered by a modification of an actuator means for the purpose of requiring different actuating forces to be provided.
It is a further object of the present invention to provide a skin incision device which can be assembled with no force required to load the components which interact to produce the incision.
It is a further object of the present invention to provide a skin incision device in which the blade is propelled by a designed controlled interaction of internal components which creates a slicing into, across and slicing out of subject tissue for the purpose of minimizing the trauma to the subject tissue.
It is a further object of the present invention to provide a skin incision device in which a consistent patterned incision can be made by the blade.
It is another object of the present invention to provide a skin incision device which reduces the introduction of undesirable components of the skin tissue into the incision area and blood sample.
It is still a further object of the present invention to provide a skin incision device that promotes rapid healing of the incision location.
It is still another object of the present invention to provide a skin incision device which has a concurrent action at the incision which locks the device and prohibits the ability of the device to be reloaded for additional uses.
It is a further object of the present invention to provide a device which is easy to use, relatively inexpensive and easy to manufacture.
These and other objections of the present invention will become apparent from a reading of the attached specification and appended claims.